This invention relates to a method and apparatus for producing equipment for handling destructive materials such as corrosive or caustic or abrasive materials. More particularly, the invention relates to a method and apparatus for producing equipment which combines a lining or barrier material having physical properties permitting it to be exposed to the destructive material and an exterior fiber glass layer to provide rigidity and strength.
Equipment for handling caustic or corrosive or abrasive materials often includes a lining or barrier formed of thermoplastic material which is encased within fiber glass or other structural material. The lining or barrier is selected to provide physical properties which can withstand the particular destructive material involved. However, the lining material often requires an encasing structure such as metal or fiber glass for structural strength and rigidity.
In such equipment it is desirable to provide a good bond between the lining and the reinforcing layer. This bond is particularly important when the equipment is exposed to vacuum which tends to cause the liner to collapse inwardly away from the reinforcing layer. The establishment of a bond is, however, difficult with certain types of thermoplastic materials. For example, the material sold under the trademark Teflon does not readily bond with bonding agents.
In the past it has been known to laminate sheets of Teflon with a glass fiber cloth or fabric by the use of heat and externally applied pressure. Such lamination, when properly performed, produces a mechanical interlocking bond between the cloth fibers and the surface of the Teflon without a chemical bonding agent. In use this laminate is often rolled to form tubes and the Teflon is welded along its longitudinal seam to provide a welded tube structure. Subsequently, the tube is encased in fiber glass which bonds with the cloth of the laminate.
The fabrication of various types of equipment for destructive materials in this manner must be very carefully accomplished. In practice it is customary to perform more than one welding operation along the seam to insure that a completely reliable weld is produced. It is also usual practice to trim the welds and to weld on additional laminate across the weld zone to provide a continuity of the cloth in the area of the weld.
Other prior art is disclosed in Japanese patent application No. 40,913 published Dec. 3, 1973, and in U.S. Pat. Nos. 2,700,631; 3,210,227; 3,325,332; 3,531,357; 3,740,291; 3,776,794; 3,802,908; 3,873,396; 3,905,853; and 3,945,867.